Microelectromechanical systems (MEMS) technology has achieved wide popularity in recent years, as it provides a way to make very small mechanical structures and integrate these structures with electrical devices on a single substrate using conventional batch semiconductor processing techniques. One common application of MEMS is the design and manufacture of sensor devices. MEMS sensors are widely used in applications such as automotive, inertial guidance systems, household appliances, game devices, protection systems for a variety of devices, and many other industrial, scientific, and engineering systems.
One example of a MEMS sensor is a MEMS accelerometer. MEMS accelerometers are sensitive to acceleration and may be configured to sense acceleration forces along one, two, or three axes or directions. One common form of MEMS accelerometer uses one or more movable structures that move under acceleration above a substrate. The movement of the movable structure changes capacitance, and an electrical circuit connected to the MEMS accelerometer structure measures the change in capacitance to determine the acceleration forces.
Continuous effort is being directed toward reducing the die size and commensurately, the cost of such MEMS accelerometers. A design approach to reducing die size is the implementation of a single proof mass design capable of detecting acceleration forces along multiple orthogonal axes. However, significant challenges arise in meeting predetermined sensitivity and reliability requirements with the implementation of a single proof mass, multiple axis sensing approach.